Political conspiracy theories may date back to ancient times, but in the modern era they can go from fringe to famous in less than a work week.

On a recent Monday, a female supporter fainted behind President Barack Obama as he delivered public remarks health care. By Wednesday, the conservative The Weekly Standard linked to a blog post alleging the woozy woman was staged, which was picked up by popular Drudge Report. On Thursday, Sarah Palin posted the story on her Facebook page, saying she had to laugh at how easy it is to believe such a theory. Less than 45 minutes later, her comments had already been shared 1,400 times and liked by more than 5,100 people. (It’s now up to 8,073 shares and 30,674 likes.)

Conspiracy theories about government and politics remain surprisingly prevalent and confoundingly persistent: Half the American public believes in at least one, according to pollsters. And experts say today’s hyper media and partisan political climate help push outlandish theories far and wide and fast.

“We’re a country that’s built on the power of people, so why should we be shocked when people insist on their own ways of viewing events?” asked Brad Meltzer, author of new book “History Decoded” and conspiracy investigation TV show “Decoded.”

An October poll by left-leaning firm Public Policy Polling found that 25 percent of voters believe Obama is secretly trying to work out a way to serve a third term, and 26 percent think Muslims are moving to implement Sharia law in U.S. courts. Among Republicans, 44 percent and 46 percent, respectively, bought into those theories.

And a poll by Fairleigh Dickinson University in January found that 36 percent of voters, including 64 percent of Republicans, believed Obama is hiding information about his background; one in four voters think the government lied about Sept. 11; and 19 percent thought the 2012 election was stolen.

Such views can also penetrate in isolated but tragic ways: An investigation into the killing of a TSA agent at Los Angeles Airport earlier this month is probing a possible connection to the alleged shooter’s beliefs in a conspiracy that the U.S. government was preparing to implement a totalitarian “new world order,” according to The Associated Press.

Experts say the modern media culture and partisan political landscape, combined with the human psychology, are driving the prevalence of wacky notions about government and politics.

“Birther theories have been with us a long time. The big difference is in those days, the people who were talking about these theories in public got laughed out. Now you have safe places to talk about this,” said Fairleigh Dickinson University political scientist and pollster Dan Cassino.

Research shows there are certain types of people who are more prone to believe in conspiracy theories, especially those who lean toward so-called “magical thinking,” which can include everything from superstitions, to interest in ESP and ghosts, to belief in angels and the devil.

Changes in the modern media environment, however, also are playing a major role in the way conspiracy theories about government interact with politics, experts say. The Internet and explosion in the number of partisan media outlets have not only allowed believers to easily and quickly find others like them to reinforce their views, but they’ve also given a digital megaphone to people actively promulgating such theories.

“With the Internet, because such a range of political perspectives and narratives can be made available and people forwarding links to like-minded people, these sort of transgressive narratives are easier to distribute. It’s not that people are more conspiratorial now, it’s just that they have greater access to it than there was even 20 or 25 years ago,” said Eric Oliver, a professor at the University of Chicago who has studied conspiracy theories.

Oliver said he became interested in conspiracy theories when he was a grad student at Berkeley, and someone gave him a piece of paper with a hand-written conspiracy theory about Queen Elizabeth and aliens.

“Today he would have a blog about it,” Oliver said.

University of Utah history professor Robert A. Goldberg, who wrote a book about conspiracy culture, also pointed to the Internet as a place that can breed and strengthen fringe ideas.

“The Internet, the expression has been coined and I think it’s a really good one, is an ‘echo chamber’,” he said. “People go on and click into blogs or chat rooms, and what they are entering is a world of consistency with no dissonance. They are seeking not information but confirmation, and they confirm what they believe and find links to other conspiracy theories they can believe in.”

“We are not a nation of fact-checkers; we are a nation of believers,” Meltzer noted. “You show me your favorite conspiracy and I’ll show you who you are.”

But it’s not just sources on the fringes that spread misinformation, researchers say: The current nature of mainstream journalism shares some of the blame.

“I wrote an essay urging caution about the media writing about conspiracy theories after Sandy Hook because it could make them more prevalent, and the risk was they were legitimatizing what was a relatively fringe notion,” said Brendan Nyhan, a Dartmouth College political scientist and media critic for the Columbia Journalism Review, referring to “false flag” conspiracy theories that were spread in the wake of the Newtown tragedy. (False flag theories is a term given to ideas that the government is behind mass casualty events but design them to look like they’re of an outside source.)

Experts also point to a rise in the number of public figures who repeat these claims and seek to benefit from them, politically and otherwise.

“We have people today who I call conspiracy sellers, who are entrepreneurs, who make a living telling us about the traitor next door,” Goldberg said. “You saw this in the 1950’s with the McCarthy period, where the Republicans were out of power and wanted to regain it. Looking at the stuff today, you have this tea party base or this very conservative base that feeds on this red meat of conspiracy theory, this red meat of doubt, and they’re riding it.”

For instance, a conspiracy that was spread by partisan outlets include the one PPP found 25 percent of Americans believing in - that Obama is secretly seeking a another four years in office, despite the constitutional prohibition. PPP pollster Jim Williams said it came to his attention when he was soliciting theories to survey.

“One thing we’re starting to see a lot on Twitter now is people thinking President Obama is secretly trying to find a way to a third term, which I didn’t see until I stated researching questions, so that’s a new one,” Williams said.

With a little searching, he found it easily on the Internet, including a Mother Jones article that traced the idea back to an advertising email distributed by Townhall.com, Newsmax, Human Events and Gingrich Marketplace, as well as mentions from popular radio hosts Alex Jones and Rush Limbaugh.

Some who have studied conspiracy beliefs say it’s also hard to ignore the changing tone of presidential conspiracy theories. While theories about Presidents Bush and Clinton focused on their alleged actions and conduct, many unsupported beliefs about Obama center on something else - his identity.

Some of the most widespread conspiracy theories about Bush were that he lied his way into the Iraq War to benefit Halliburton and Vice President Dick Cheney and that he was behind or knew in advance about the Sept. 11 attacks. Clinton was accused of being involved in the death of White House counsel Vince Foster, who committed suicide, and of smuggling drugs and arms.

“Obama conspiracy theories have been more identity-focused. So, he looks different and he has a different kind of name, so the conspiracy theories have suggested he is a Muslim or he was not born in this country or he’s trying to implement Muslim law,” Nyhan said.

“I think that the fact that he’s a black man is incredibly significant, when you think of black people fighting since 1865 to have citizenship, now you have the most powerful black leader in American history and his citizenship is being questioned,” Goldberg said.

At the same time, the conspiracy theories about Obama tap into a long-running strain of belief, Goldberg said.

“That is the ‘Manchurian candidate,’ that somebody has been planted who has been given money to go to school, his grades have been altered, now he’s in the Oval Office and he’s been planted to enact this larger catastrophe to create a new world order,” Goldberg said.

In addition, political ideology can play a role in an individual’s readiness to believe government-related conspiracy theories. For one, studies show that members of whichever party is out of power are more likely to buy in.

While long-term data on whether one ideology is more susceptible to conspiratorial beliefs is hard to come by, there is some research to suggest that Republicans on average are more prone to it. Cassino said that when you compare the increases in belief in conspiracy theories when the parties are out of power, the GOP spikes are higher.

“Republicans are more likely to believe bad things about the other side,” Cassino said. “If you compare white Republicans to white Democrats, the difference is even starker, because African Americans are more likely to believe conspiracy theories.”

Part of why conspiracy theories about government and politics persist is that they can be psychologically comforting in difficult times, especially after a calamitous event, from the relatively minor lost election to a school shooting to a wrenching national tragedy.

“Conspiracies in a strange way are us, they’re our greatest fears brought to life, and sadly every great horror instantly becomes a breeding ground for conspiracy,” Meltzer said. “JFK certainly gives a great example. If you look historically in the 1960s, you know who killed JFK? We thought it was the communists, the Cubans, the Russians, our great enemies at the time. In the ‘70s we thought it was the government, in the Watergate era. In the ‘80s, it was the mob. Decade by decade, if you want to know who killed Kennedy, it was whoever America was most scared of at the time.”